Non‐Precious Metal Catalysts for Acidic Oxygen Evolution in Proton Exchange Membrane Water Electrolysis: Degradation Challenges and Regulation Strategies

ABSTRACT Proton exchange membrane water electrolysis (PEMWE) is a promising technology for green hydrogen production, but its large‐scale application is still limited by the high cost and limited supply of Ir‐based anode catalysts. Non‐precious metal catalysts provide abundant and structurally tunable alternatives, yet they generally suffer from poor stability under acidic oxygen evolution reaction (OER) conditions. Their high activity often relies on reactive metal centers, oxygen defects, reconstructed surfaces, or flexible coordination environments, which may also increase the risk of structural damage and material loss, causing degradation of the catalyst and lower activity. This Review discusses the thermodynamic basis of catalyst instability and the primary catalyst degradation processes under operation, including proton‐ and potential‐driven metal dissolution, interfacial water‐assisted corrosion and oxygen‐sublattice depletion, as well as degradation amplification effect induced by dynamic operation. The coupling among these degradation processes and their dependence on operating conditions are further elaborated. The degradation risks associated with the adsorbate evolution, lattice oxygen, oxide path, and mixed OER pathways are then compared. Based on these challenges, stability‐oriented strategies are summarized as intrinsic structure tuning, heterointerfacial engineering, proton/water microenvironment modulation, and dissolution‐redeposition regulation. Finally, recent advances in both half‐cell measurements and practical PEMWE devices are reviewed, and future research priorities are outlined with respect to standardized testing protocols, quantitative material tracking, rational catalyst design, and scalable device development.